This invention relates to the field of flexible hoses and more particularly to flexible hoses used for circulation of fluids in radiant heating systems in homes and businesses. Typical prior art hoses for such applications are disclosed, for example, in Chiles et al. U.S. Pat. No. 4,779,673 and in Chiles et al. U.S. Pat. No. 5,488,975.
Often times such hoses supply water or other heating fluid to heat exchangers located in floors, ceilings, roofs and concrete or asphalt slabs. The hoses may be embedded in the surfaces to be heated, and it is desirable that they be flexible for ease of installation. A significant problem with such hoses is that they are subject to gas infiltration and exfiltration. Oxygen is particularly troublesome, because it is easily ingested from the outside environment. Once oxygen has gained entry to such a heating system, it deteriorates the hoses and corrodes the pumping system.
Chiles '975 discloses a flexible heating system hose having an oxygen barrier layer in the form of a thin plastic film such as ethylene vinyl alcohol. Alternatively, the patent suggests the use of an aluminum barrier layer. Both of these barriers have problems. Oxygen is able to penetrate all known plastic films, at least to some small degree. Aluminum is substantially impermeable to oxygen, but it does not bond well against other materials. Consequently prior art hoses having aluminum barrier layers tend to delaminate under stress.
A number of other prior art patents disclose flexible hoses incorporating metallic layers of one type or another. Such disclosures appear, for example, in Hane et al. U.S. Pat. No. 4,559,973, Campbell et al. U.S. Pat. No. 4,758,455, Davis U.S. Pat. No. 5,182,147, Yoshikawa et al. U.S. Pat. No. 5,271,977 and Spurgett U.S. Pat. No. 5,398,729. None of these prior art references teach a flexible hose having an aluminum barrier bonded therein with sufficient adhesion to avoid delamination over a long period of time in a heating system environment. Typically such prior art hoses are used for fuel and vapor transmission and are constructed by coating the metal strip on both sides with an adhesive which may, for example, be an adhesive made from a copolymer of ethylene and a monomer having a reactive carboxyl group, as taught in Campbell et al.
It is therefore seen that there is a need for a flexible hose incorporating an aluminum barrier layer, and able to resist delamination in a heating system environment.